These are all taken with M8.2 and M9. You could argue that you could mount a similar lens on a Nikon body and still work with higher ISO. That is correct and it would give you a lot of freedom, but the camera would not be discreet. The Leica has not that high ISO performance that Nikon has, but it still produces great output at low light within a certain ISO range. Test if ISO 1000 or 1200 at F1.4 would give you enough room for your photography.

I know what you mean with the 'smell f the street'. I have those but they are older and could not be part of the M9 review. D!RK